I have riverbanks, we need to find a way to prevent erosion .

Building a retaining wall will help. Here are some sites that explain options.

https://www.erosionpollution.com/river-bank-erosion.html

http://homeguides.sfgate.com/plants-stop-erosion-creek-banks-30129.html

Sometimes fema can help too. I would contact your local authorities and see what programs may be in place to help you out!

https://www.fema.gov/appeal/218769

https://www.wikihow.com/Prevent-Soil-Erosion

By chance the last question I answered may help you too. Try ground cover. https://www.countryliving.com/gardening/garden-ideas/how-to/g789/ground-cover-flowers-0509/

Would this type of application work for you? The blocks have a hook on the back... so they can't slide forward.... but.... they might need to have a poured footer... for a riverbank

It is very difficult to stop running water from eroding it's banks. It is the nature of the flow to turn. It happens when the water on the bottom rolls to become the water on the top. The movement looks a lot like a curled piece of ribbon. Plus when rain water is added it speeds things up and the flow becomes turbulent. You will have a fight on your hands. The Army Corp of Engineers' library might be of some help.

Where do you find their library info?

Whoops! oh well....